Disposal of intact Compact Discs (CDs) and Digital Video Discs (DVDs), including CD-Rs, CD-RWs, DVD-Rs and DVD-RWs, risks disclosure of information contained on the media, similar to the risks faced during disposal of intact paper documents. The paper security problem has been largely addressed, with the widespread availability of relatively inexpensive paper shredders for home, business and industrial environments. However, an equivalently reliable and cost-effective solution for rendering discs unreadable is not in widespread use.
As CD and DVD writers are becoming more affordable, there is an increase in the use of these types of discs for storage of confidential information. Businesses store trade secrets and personal information that is subject to privacy restrictions. Home users often write financial data and highly personal information on CDs and DVDs. If these are placed in the trash in an intact state, the confidential information may then be read by anyone who removes the discs from the trash.
Common methods to render a disc unreadable include burning, pulverizing, shattering, snapping, grinding and scratching the label side of the disc into the data layer. Burning and pulverizing may be quite effective in rendering a disc unreadable. Unfortunately, those methods may require expensive equipment. Shattering and snapping can be difficult for people without either the required strength or tools. Additionally, shattering or snapping a disc presents a risk of injury from sharp, flying shards. Multiple models of disc grinders are available, although their size, cost and requirement for electric power may limit their desirability for certain potential users.
Scratching into the data layer can often be done easily with any sharp instrument. However, it presents risks, including injury and unintentional damage to other surfaces. Further, the damage to the disc may not be complete enough to render a disc unreadable. One reason that scratching a disc may not be adequate is that a typical disc user may not be aware of the physical layout of the data on a CD or DVD surface, and therefore may not sufficiently damage the critical data areas.
A CD typically contains a volume descriptor in sector 16, which is within a fraction of an inch of the innermost portion of the optically-readable section of the disc. Disc readers typically first read the volume descriptor, also known as an index, to determine the contents of the disc. If this section is damaged or missing, the majority of disc readers may be unable to read the disc. However, due to its small size and its location near the innermost part of the optically-readable area, it is easy to miss with uncontrolled, random scratching. A disc with an intact volume descriptor may still be readable, and files whose data area has not been adequately damaged may be fully recoverable. Therefore, simply scratching a disc randomly with a sharp instrument does not provide safe, quality-controlled destruction.